Tonometer air pulse generator

Abstract

An air pulse generator for a non-contact tonometer comprises a bi-directional linear motor drivably connected to a compression mechanism and responsive to an applanation signal for reducing unnecessary air pulse energy delivered to an eye. Upon receiving the applanation signal from an applanation detector, a motor controller reverses current flow in the coil of the motor to create a reverse electromagnetic force to stop generation of the air pulse. In a first embodiment, the linear motor includes a moving permanent magnet armature for reversibly driving the compression mechanism, while in a second embodiment, the linear motor includes a moving coil for reversibly driving the compression mechanism.

What is claimed is: 
     
       1. A non-contact tonometer for making a measurement of intraocular pressure of an eye, said non-contact tonometer having an outlet for directing an increasing velocity air pulse toward said eye and detecting means for generating a signal indicating applanation of the eye caused by said air pulse, which comprises: compression means communicating with said outlet for generating said air pulse;   a motor drivably connected to said compression means;   energizing means connected to said motor for providing force to move said compression means in a first direction along an axis and produce said air pulse; and   reversing means connected to said energizing means for providing force to stop generation of said air pulse directly in response to said signal generated during said measurement.   
     
     
       2. The non-contact tonometer according to claim 1, wherein said compression means includes a bellows pump. 
     
     
       3. The non-contact tonometer according to claim 1, wherein said compression means includes a diaphragm pump. 
     
     
       4. The non-contact tonometer according to claim 1, wherein said compression means includes a piston pump. 
     
     
       5. The non-contact tonometer according to claim 1, wherein said force to stop generation of said air pulse is sufficient to move said compression means in a second direction opposite said first direction. 
     
     
       6. The non-contact tonometer according to claim 5, wherein said compression means includes a bellows pump. 
     
     
       7. The non-contact tonometer according to claim 5, wherein said compression means includes a diaphragm pump. 
     
     
       8. The non-contact tonometer according to claim 5, wherein said compression means includes a piston pump. 
     
     
       9. The non-contact tonometer according to claim 1, wherein said motor is a linear motor. 
     
     
       10. The non-contact tonometer according to claim 9, wherein said linear motor includes a permanent magnet connected to said compression means and axially movable relative to a fixed coil. 
     
     
       11. The non-contact tonometer according to claim 9, wherein said linear motor includes a coil connected to said compression means and axially movable relative to a fixed permanent magnet. 
     
     
       12. The non-contact tonometer according to claim 11, wherein said movable coil is a voice coil. 
     
     
       13. The non-contact tonometer according to claim 9, wherein said linear motor includes a coil connected to said compression means and axially movable relative to a fixed electromagnet. 
     
     
       14. The non-contact tonometer according to claim 13, wherein said movable coil is a voice coil. 
     
     
       15. The non-contact tonometer according to claim 14, wherein said compression means includes a diaphragm pump. 
     
     
       16. The non-contact tonometer according to claim 9, wherein said compression means includes a bellows pump. 
     
     
       17. The non-contact tonometer according to claim 9, wherein said compression means includes a diaphragm pump. 
     
     
       18. The non-contact tonometer according to claim 9, wherein said compression means includes a piston pump. 
     
     
       19. A non-contact tonometer for making a measurement of intraocular pressure of an eye, said non-contact tonometer having an outlet for directing an increasing velocity air pulse toward said eye and detecting means for generating a signal indicating applanation of the eye caused by said air pulse, which comprises: compression means communicating with said outlet for generating said air pulse;   a linear motor drivably connected to said compression means;   energizing means connected to said linear motor for providing force to move said compression means in a first direction along an axis and produce said air pulse; and   short circuit means for disconnecting said energizing means from said motor directly in response to said signal generated during said measurement.